Zhiqiang (John) Zhai

The inlet air temperature of HVAC rooftop units (RTUs) is commonly used in building system design and performance evaluation, playing a critical role in system sizing, determination of outdoor air ...

This study numerically investigates the transient thermal response of a raised-floor data center under dynamic AI server loads. Power profiles of DGX A100 servers running GEMM, VGG-19, and ResNet-152 workloads were used as time-varying boundary conditions in CFD simulations. Six load scenarios were analyzed to evaluate the dynamic responses of cooling capacity, rack inlet and outlet temperatures, and net airflow rate. The results show that the response lag of air-conditioning units causes a temporary mismatch between cooling supply and server heat dissipation, leading to transient inlet-temperature fluctuations. Fluctuating workloads produce larger outlet-temperature amplitudes and higher temperature change rates than stable workloads, while mixed workloads change the overall fluctuation intensity and affect neighboring-rack airflow through cold-aisle pressure interactions. These findings can support workload-aware rack arrangement and adaptive cooling control for future AI-oriented data centers.

Gorontalo Province is one of the developing regions in Indonesia. The province has been actively building apartments since 2009. The construction increases population density and energy use intensity. Consequently, demand for electricity power rises. Renewable energy such as rooftop photovoltaics has the potential as a power source for the apartments, considering the abundant solar radiation in Gorontalo which is located near the equator line. Three apartments representing three levels of the inhabitant’s income are selected as study case for the application of photovoltaic (PV) on roof to achive net zero energy building. Simulation of PV energy to power the buildings is conducted using photovoltaic geographical information system (PVGIS). By utilizing monthly electrical bill data, it is found that PV on roof is sufficient to cover the building energy demand and achieve net zero energy building (NZEB). However, there is uncertainty of the fluctuation of energy demand due to the tenant’s energy consumption behaviour. The consumption intensity is limited only by the installed power on each apartment unit. PV on roof alone is unable to provide the need if it is employed to power the unit to the maximum extent.